Light emitting device and display panel

Abstract

The invention provides a light-emitting device and a display panel, and belongs to the technical field of display. The light-emitting device of the present disclosure includes an anode, a cathode, a plurality of light-emitting units disposed between the anode and the cathode, and charge generation and separation units disposed between adjacent light-emitting units. The plurality of light-emitting units comprise a first light-emitting unit and a second light-emitting unit, and the first light-emitting unit is closer to the anode than the second light-emitting unit; the first light-emitting unit comprises a first light-emitting layer and a first hole transport subunit which is arranged on the first light-emitting layer and is close to the anode; the second light-emitting unit comprises a second light-emitting layer and a second hole transport subunit which is arranged on the second light-emitting layer and is close to the anode; the thickness of the first hole transport subunit of the first light-emitting unit is larger than that of the second hole transport subunit of the second light-emitting unit.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the technical field of display, and particularly relates to a light-emitting device and a display panel. BACKGROUND

[0002] Tandem OLED emerges in the development of OLED. Tandem OLED has the advantages of high efficiency and high brightness. However, the Tandem OLED in the related art has the problem that the light-emitting efficiency and the lifespan of different color light-emitting devices are inconsistent. SUMMARY

[0003] The present disclosure aims to at least solve one of the technical problems existing in the prior art, and provides a light-emitting device and a display panel.

[0004] In a first aspect, a technical solution adopted to solve the technical problems of the present disclosure is a light-emitting device, comprising an anode, a cathode, a plurality of light-emitting units arranged between the anode and the cathode, and a charge generation separation unit arranged between adjacent light-emitting units.

[0005] The plurality of light-emitting units comprises at least one first light-emitting unit and one second light-emitting unit, and the first light-emitting unit is closer to the anode than the second light-emitting unit.

[0006] The first light-emitting unit comprises a first light-emitting layer and a first hole transport sub-unit arranged close to the anode of the first light-emitting layer; and the second light-emitting unit comprises a second light-emitting layer and a second hole transport sub-unit arranged close to the anode of the second light-emitting layer.

[0007] The thickness of the first hole transport sub-unit of the first light-emitting unit is greater than the thickness of the second hole transport sub-unit of the second light-emitting unit.

[0008] In some embodiments, the charge generation separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer arranged in sequence away from the anode; a surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; a surface of the first light-emitting layer close to the N-type doped charge generation layer is a second surface, and the distance from the first surface to the second surface is a first distance.

[0009] When the light-emitting device is a red light-emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 6 and 10.

[0010] when the light emitting device is a green light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 5 and 8;

[0011] when the light emitting device is a blue light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 4 and 6.

[0012] In some embodiments, when the light emitting device is a red light emitting device, the thickness of the first hole transport sub-unit is between 170 nm and 230 nm;

[0013] when the light emitting device is a green light emitting device, the thickness of the first hole transport sub-unit is between 130 nm and 170 nm;

[0014] when the light emitting device is a blue light emitting device, the thickness of the first hole transport sub-unit is between 90 nm and 130 nm.

[0015] In some embodiments, the first distance is between 15 nm and 30 nm.

[0016] In some embodiments, the first light emitting unit further comprises a first hole blocking layer disposed on the first light emitting layer close to the cathode; the thickness of the first hole blocking layer is between 5 nm and 10 nm.

[0017] In some embodiments, the charge generation and separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer disposed in sequence in a direction away from the anode; the surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; the surface of the second light emitting layer close to the N-type doped charge generation layer is a third surface, and the second distance is the distance from the third surface to the closest first surface;

[0018] the surface of the second light emitting layer close to the cathode side is a fourth surface, and the third distance is the shortest distance from the fourth surface to the cathode;

[0019] when the light emitting device is a red light emitting device, the ratio of the second distance to the third distance is between 2 and 3.2;

[0020] when the light emitting device is a green light emitting device, the ratio of the second distance to the third distance is between 1.8 and 2.8;

[0021] when the light emitting device is a blue light emitting device, the ratio of the second distance to the third distance is between 1.6 and 2.6.

[0022] In some embodiments, when the light emitting device is a red light emitting device, the second distance is between 80 nm and 110 nm; when the light emitting device is a green light emitting device, the second distance is between 65 nm and 95 nm; when the light emitting device is a blue light emitting device, the second distance is between 55 nm and 85 nm.

[0023] In some embodiments, when the light emitting device is a red light emitting device, the thickness of the second hole transport sub-unit is between 70 nm and 90 nm; when the light emitting device is a green light emitting device, the thickness of the second hole transport sub-unit is between 60 nm and 80 nm; when the light emitting device is a blue light emitting device, the thickness of the second hole transport sub-unit is between 50 nm and 70 nm.

[0024] In some embodiments, the first hole transport sub-unit comprises at least a first hole transport layer; the second hole transport sub-unit comprises at least a second hole transport layer;

[0025] The structural general formula (I) of the material of the first hole transport layer and the material of the second hole transport layer is as follows:

[0026]

[0027] wherein, Ar1-Ar3 are each independently selected from any one of hydrogen, deuterium, nitrile group, nitro group, hydroxyl group, carbonyl group, ester group, imide group, amide group, alkyl group, cycloalkyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, alkenyl group, silyl group, boron group, amine group, aryl phosphine group, phosphine oxide group, aryl group, heteroaryl group; or, any adjacent groups among Ar1-Ar3 combine to form a ring; N represents a nitrogen atom.

[0028] In some embodiments, the first hole transport sub-unit comprises at least a first hole transport layer; the second hole transport sub-unit comprises at least a second hole transport layer;

[0029] The structural general formula (II) of the material of the first hole transport layer and the material of the second hole transport layer is as follows:

[0030]

[0031] wherein, Ar4-Ar7are each independently selected from any one of hydrogen, deuterium, nitrile group, nitro group, hydroxyl group, carbonyl group, ester group, imide group, amide group, alkyl group, cycloalkyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, alkenyl group, silyl group, boron group, amine group, aryl phosphine group, phosphine oxide group, aryl group, heteroaryl group; or, any adjacent groups of Ar4-Ar7combine to form a ring; L represents a substituted or unsubstituted arylene group or heteroarylene group.

[0032] In some embodiments, Ar1-Ar7are selected from any one of the following structures:

[0033]

[0034]

[0035] wherein, * represents the position of the general structure (I) or the position of the general structure (II).

[0036] In some embodiments, L is selected from any one of the following structures:

[0037]

[0038]

[0039] In some embodiments, the first hole transport sub-unit comprises, in sequence from the direction away from the anode, a first hole injection layer, a first hole transport layer, and a first electron blocking layer; and the second hole transport sub-unit comprises, in sequence from the direction away from the anode, a second hole transport layer and a second electron blocking layer.

[0040] In a second aspect, the embodiments of the present disclosure further provide a display panel, comprising a plurality of light emitting devices of different colors; the plurality of light emitting devices of different colors comprise red light emitting devices, green light emitting devices, and blue light emitting devices;

[0041] The materials of the first electron blocking layers corresponding to the red light emitting devices, the green light emitting devices, and the blue light emitting devices are different; and the materials of the second electron blocking layers corresponding to the red light emitting devices, the green light emitting devices, and the blue light emitting devices are different.

[0042] The materials of the first light emitting layers corresponding to the red light emitting devices, the green light emitting devices, and the blue light emitting devices are different; and the materials of the second light emitting layers corresponding to the red light emitting devices, the green light emitting devices, and the blue light emitting devices are different.

[0043] In some embodiments, the light emitting device comprises an anode, a cathode, a plurality of light emitting units disposed between the anode and the cathode, and a charge generation separation unit disposed between adjacent light emitting units; the plurality of light emitting units comprises a first light emitting unit and a second light emitting unit, and the first light emitting unit is closer to the anode than the second light emitting unit; the first light emitting unit comprises a first light emitting layer, and a first hole transport sub-unit disposed on the first light emitting layer close to the anode; the second light emitting unit comprises a second light emitting layer, and a second hole transport sub-unit disposed on the second light emitting layer close to the anode;

[0044] The charge generation separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer disposed in sequence away from the anode; a surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; a surface of the first light emitting layer close to the N-type doped charge generation layer is a second surface, and a distance from the first surface to the second surface is a first distance;

[0045] For the red light emitting device, a ratio of a thickness of the first hole transport sub-unit to the first distance is between 6 and 10; for the green light emitting device, a ratio of a thickness of the first hole transport sub-unit to the first distance is between 5 and 8; and for the blue light emitting device, a ratio of a thickness of the first hole transport sub-unit to the first distance is between 4 and 6.

[0046] In some embodiments, for the red light emitting device, the thickness of the first hole transport sub-unit is between 170 nm and 230 nm; for the green light emitting device, the thickness of the first hole transport sub-unit is between 130 nm and 170 nm; and for the blue light emitting device, the thickness of the first hole transport sub-unit is between 90 nm and 130 nm.

[0047] In some embodiments, the first distance is between 15 nm and 30 nm.

[0048] In some embodiments, the light emitting device comprises an anode, a cathode, a plurality of light emitting units disposed between the anode and the cathode, and a charge generation separation unit disposed between adjacent light emitting units; the plurality of light emitting units comprises a first light emitting unit and a second light emitting unit, and the first light emitting unit is closer to the anode than the second light emitting unit; the first light emitting unit comprises a first light emitting layer, and a first hole transport sub-unit disposed on the first light emitting layer close to the anode; the second light emitting unit comprises a second light emitting layer, and a second hole transport sub-unit disposed on the second light emitting layer close to the anode;

[0049] The charge generation separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer arranged in sequence in a direction away from the anode; a surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; a surface of the second light-emitting layer close to the N-type doped charge generation layer is a third surface, and a distance from the third surface to the nearest first surface is a second distance; a surface of the second light-emitting layer close to the cathode side is a fourth surface, and a shortest distance from the fourth surface to the cathode is a third distance;

[0050] For the red light-emitting device, the ratio of the second distance to the third distance is between 2 and 3.2; for the green light-emitting device, the ratio of the second distance to the third distance is between 1.8 and 2.8; and for the blue light-emitting device, the ratio of the second distance to the third distance is between 1.6 and 2.6.

[0051] In some embodiments, for the red light-emitting device, the second distance is between 80 nm and 110 nm; for the green light-emitting device, the second distance is between 65 nm and 95 nm; and for the blue light-emitting device, the second distance is between 55 nm and 85 nm.

[0052] In some embodiments, for the red light-emitting device, the thickness of the second hole transport sub-unit is between 70 nm and 90 nm; for the green light-emitting device, the thickness of the second hole transport sub-unit is between 60 nm and 80 nm; and for the blue light-emitting device, the thickness of the second hole transport sub-unit is between 50 nm and 70 nm. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 A structural schematic diagram of a light-emitting device provided by an embodiment of the present disclosure;

[0054] Figure 2 A sub-unit schematic diagram of a light-emitting unit provided by an embodiment of the present disclosure;

[0055] Figure 3 A specific structural schematic diagram of a carrier transport sub-unit provided by an embodiment of the present disclosure;

[0056] Figure 4 A schematic diagram of film layer spacing in a light-emitting device provided by an embodiment of the present disclosure;

[0057] Figure 5 A specific structural schematic diagram of another carrier transport sub-unit provided by an embodiment of the present disclosure;

[0058] Figure 6 A schematic diagram of a display panel provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0059] In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the following will be combined with the accompanying drawings for the embodiments of the present disclosure to make a clear and complete description of the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure and not all the embodiments. The components of the embodiments of the present disclosure generally described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the accompanying drawings is not intended to limit the scope of the claimed present disclosure, but only represents selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present disclosure.

[0060] Unless otherwise defined, technical or scientific terms used in the present disclosure should have the same meaning as commonly understood by one of ordinary skill in the art to which this present disclosure belongs. The terms "first", "second", and similar terms used in the present disclosure do not imply any order, quantity, or importance, but are used to distinguish different components. Similarly, the terms "one", "a", or "the" and similar terms do not denote the number restriction, but mean that there is at least one. The terms "include", "comprise", and similar terms mean that the elements or objects before the term encompass the elements or objects listed after the term and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships may also be changed accordingly.

[0061] In the present disclosure, "a plurality of or several" means two or more. The term "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0062] In the related art, the carrier transport path in the Tandem device includes: in the first light-emitting unit, holes are transported from the anode to the first light-emitting layer; and electrons are transported from the interface between the N-CGL layer and the P-CGL layer to the first light-emitting layer. In the second light-emitting unit, holes are transported from the interface between the N-CGL layer and the P-CGL layer to the second light-emitting layer; and electrons are transported from the cathode to the first light-emitting layer. However, a hole blocking layer is often arranged between the N-CGL layer and the first light-emitting layer, which is a combination of one or more organic layers, mainly used for transporting electrons and blocking holes; in addition, when the hole blocking layer is in direct contact with the N-CGL layer, it is also used to block the metal ions doped in the N-CGL layer to prevent the migration of metal ions, so there is a large energy level barrier between the hole blocking layer and the N-CGL layer, resulting in a low electron transport rate. At the same time, the hole transport material currently used has a faster hole transport speed and a higher hole injection efficiency, which causes an imbalance in the transport rates of holes and electrons, ultimately leading to the inability of holes and electrons to recombine in the first light-emitting layer or a small recombination area, thereby affecting the luminous efficiency and service life of the light-emitting device.

[0063] In view of this, the embodiments of the present disclosure provide a light-emitting device which substantially eliminates one or more of the problems caused by the limitations and defects of the related art.

[0064] Figure 1 A structural schematic diagram of the light-emitting device provided by the embodiments of the present disclosure is shown in Figure 1 The light-emitting device includes an anode 1, a cathode 2, a plurality of light-emitting units arranged between the anode 1 and the cathode 2, and a charge generation separation unit 4 arranged between adjacent light-emitting units. Among them, the plurality of light-emitting units at least includes a first light-emitting unit 31 and a second light-emitting unit 32, and the first light-emitting unit 31 is closer to the anode 1 than the second light-emitting unit 32. That is, the light-emitting device of the present disclosure is a Tandem OLED device, which has the advantages of high efficiency and high brightness.

[0065] Figure 2 A subunit schematic diagram of the light-emitting unit provided by the embodiments of the present disclosure is shown in Figure 1 The first light-emitting unit 31 includes a first light-emitting layer EML1 and a first hole transport subunit 311 arranged near the anode 1 of the first light-emitting layer EML1; and the second light-emitting unit 32 includes a second light-emitting layer EML2 and a second hole transport subunit 321 arranged near the anode 1 of the second light-emitting layer EML2. Among them, the first hole transport subunit 311 is mainly used for transporting holes generated by the anode 1 or the charge generation separation unit 4 to improve the hole transport efficiency. The second hole transport subunit 321 is mainly used for transporting holes generated by the charge generation separation unit 4 to improve the hole transport efficiency.

[0066] As shown in Figure 2 The first light-emitting unit 31 further comprises a first electron transport sub-unit 312 arranged on the side of the first light-emitting layer EML1 close to the cathode 2; and the second light-emitting unit 32 further comprises a second electron transport sub-unit 322 arranged on the side of the second light-emitting layer EML2 close to the cathode 2. The first electron transport sub-unit 312 is mainly used for transporting the electrons generated by the charge generation and separation unit 4, so as to improve the electron transport efficiency; and the second electron transport sub-unit 322 is mainly used for transporting the electrons generated by the cathode 2, so as to improve the electron transport efficiency.

[0067] For example, the plurality of light-emitting units comprises one first light-emitting unit 31 and one second light-emitting unit 32. For another example, the plurality of light-emitting units comprises a plurality of first light-emitting units 31 and one second light-emitting unit 32. In the case of comprising a plurality of first light-emitting units 31 and one second light-emitting unit 32, the thickness of the first hole transport sub-unit 311 of at least part of the first light-emitting units 31 is greater than the thickness of the second hole transport sub-unit 321 of the second light-emitting unit 32.

[0068] For example, the light-emitting device comprises one first light-emitting unit 31, one charge generation and separation unit 4 and one second light-emitting unit 32. Under the action of an electric field, the anode 1 generates holes, and the cathode 2 generates electrons; the charge generation and separation unit 4 also generates holes and electrons, and separates them. The holes generated by the anode 1 are transported to the first light-emitting layer EML1 through the first hole transport sub-unit 311, and the electrons generated by the charge generation and separation unit 4 can be transported to the first light-emitting layer EML1 through the first electron transport sub-unit 312; and the holes generated by the charge generation and separation unit 4 are transported to the second light-emitting layer EML2 through the second hole transport sub-unit 321, and the electrons generated by the cathode 2 can be transported to the second light-emitting layer EML2 through the second electron transport sub-unit 322. The holes and electrons migrate to the first light-emitting layer EML1 (or the second light-emitting layer EML2), and excitons are generated by recombination in the first light-emitting layer EML1 (or the second light-emitting layer EML2), and the excitons radiate light by jumping transition.

[0069] Figure 3 A specific structure diagram of a carrier transport sub-unit provided by the embodiment of the present disclosure is shown. For example, as shown in Figure 3As shown, the first hole transport sub-unit 311 includes at least a first hole transport layer HTL1, the second hole transport sub-unit 321 includes at least a second hole transport layer HTL2, the first electron transport sub-unit 312 includes at least a first hole blocking layer HBL1, and the second electron transport sub-unit 322 includes at least a second hole blocking layer HBL2. The first hole blocking layer HBL1 is a combination of one or more organic layers, mainly used for transporting electrons and blocking holes; in addition, when the first hole blocking layer HBL1 is in direct contact with the charge generation and separation unit 4, it is also used to block the metal ions doped in the charge generation and separation unit 4, preventing the migration of metal ions, so there is a large energy level barrier between the first hole blocking layer HBL1 and the charge generation and separation unit 4, resulting in a low electron transport rate.

[0070] The thickness of the first hole transport sub-unit 311 of the first light emitting unit 31 is greater than the thickness of the second hole transport sub-unit 321 of the second light emitting unit 32 in the embodiments of the present disclosure. Compared with the prior art, the embodiments of the present disclosure adjust the thickness of the first hole transport sub-unit 311 and / or the thickness of the second hole transport sub-unit 321, for example, increase the thickness of the first hole transport sub-unit 311 of the first light emitting unit 31, so that the thickness of the first hole transport sub-unit 311 is greater than the thickness of the second hole transport sub-unit 321, that is, the hole transport path of the anode 1→the first light emitting layer EML1 is increased, so as to reduce the hole transport rate of the first hole transport sub-unit 311, thereby balancing the hole transport rate of the anode 1→the first light emitting layer EML1 and the electron transport rate of the charge generation and separation unit 4→the first light emitting layer EML1, so as to ensure that holes and electrons recombine in the first light emitting layer EML1, and further ensure the light emitting stability of the light emitting device.

[0071] In some embodiments, as Figure 3 As shown, the charge generation and separation unit 4 includes an N-type doped charge generation layer N-CGL and a P-type doped charge generation layer P-CGL arranged in sequence away from the anode 1; the surface of the N-type doped charge generation layer N-CGL in contact with the P-type doped charge generation layer P-CGL is a first surface; the surface of the first light emitting layer EML1 close to the N-type doped charge generation layer N-CGL is a second surface, and the distance between the first surface and the second surface is a first distance L1. Here, the first distance L1 can be understood as the transmission distance of the electrons generated by the charge generation and separation unit 4, that is, the length of the electron transport path from the starting point of generation to the first light emitting layer EML1.

[0072] Because the materials of the light emitting layers of different color light emitting devices are different, the materials of the sub-film layers in the first hole transport sub-unit 311 can be different, so the hole mobility and the energy level difference between the film layers corresponding to different color light emitting devices are different.

[0073] Figure 4 A schematic diagram of the distance between the film layers in the light-emitting device provided by the embodiments of the present disclosure is shown in FIG. 1. Figure 4 As shown in FIG. 1, when the light-emitting device is a red light-emitting device R, the ratio of the thickness R_H of the first hole transport sub-unit 311 to the first distance L1 is between 6 and 10. The embodiments are directed to the first light-emitting unit 31 corresponding to the red light-emitting device R, and the distance of the hole transport path and the distance of the electron transport path in the first light-emitting unit 31 are adjusted in coordination. The ratio of the thickness R_H of the first hole transport sub-unit 311 to the first distance L1 is between 6 and 10, thereby ensuring the transmission balance of the carriers (holes and electrons) in the red light-emitting device R.

[0074] Specifically, when the light-emitting device is a green light-emitting device G, the ratio of the thickness G_H of the first hole transport sub-unit 311 to the first distance L1 is between 5 and 8. The embodiments are directed to the first light-emitting unit 31 corresponding to the green light-emitting device G, and the distance of the hole transport path and the distance of the electron transport path in the first light-emitting unit 31 are adjusted in coordination. The ratio of the thickness G_H of the first hole transport sub-unit 311 to the first distance L1 is between 5 and 8, thereby ensuring the transmission balance of the carriers (holes and electrons) in the green light-emitting device G.

[0075] Specifically, when the light-emitting device is a blue light-emitting device B, the ratio of the thickness B_H of the first hole transport sub-unit 311 to the first distance L1 is between 4 and 6. The embodiments are directed to the first light-emitting unit 31 corresponding to the blue light-emitting device B, and the distance of the hole transport path and the distance of the electron transport path in the first light-emitting unit 31 are adjusted in coordination. The ratio of the thickness B_H of the first hole transport sub-unit 311 to the first distance L1 is between 4 and 6, thereby ensuring the transmission balance of the carriers (holes and electrons) in the blue light-emitting device B.

[0076] In a possible implementation, as shown in FIG. 1, when the light-emitting device is a red light-emitting device R, the thickness R_H of the first hole transport sub-unit 311 is between 170 nm and 230 nm. Compared with the prior art (the thickness of the first hole transport sub-unit 311 of the red light-emitting device R is about 65 nm), this implementation increases the thickness R_H of the first hole transport sub-unit 311 of the red light-emitting device R, that is, the length of the hole transport path, to reduce the hole transport rate, thereby balancing the transport rates of holes and electrons, making them recombine in the first light-emitting layer REML1, and ensuring the light-emitting stability of the red light-emitting device R. Figure 4 Optionally, the thickness R_H of the first hole transport sub-unit 311 is 170 nm, 200 nm, or 230 nm.

[0077] In a possible implementation, as shown in FIG. 1, when the light-emitting device is a green light-emitting device G, the thickness G_H of the first hole transport sub-unit 311 is between 150 nm and 200 nm. Compared with the prior art (the thickness of the first hole transport sub-unit 311 of the green light-emitting device G is about 65 nm), this implementation increases the thickness G_H of the first hole transport sub-unit 311 of the green light-emitting device G, that is, the length of the hole transport path, to reduce the hole transport rate, thereby balancing the transport rates of holes and electrons, making them recombine in the first light-emitting layer REML1, and ensuring the light-emitting stability of the green light-emitting device G.

[0078] In a possible implementation, as shown in FIG. 1, when the light-emitting device is a blue light-emitting device B, the thickness B_H of the first hole transport sub-unit 311 is between 130 nm and 170 nm. Compared with the prior art (the thickness of the first hole transport sub-unit 311 of the blue light-emitting device B is about 65 nm), this implementation increases the thickness B_H of the first hole transport sub-unit 311 of the blue light-emitting device B, that is, the length of the hole transport path, to reduce the hole transport rate, thereby balancing the transport rates of holes and electrons, making them recombine in the first light-emitting layer REML1, and ensuring the light-emitting stability of the blue light-emitting device B.Figure 4 As shown, when the light emitting device is a green light emitting device G, the thickness G H of the first hole transport sub-unit 311 is between 130 nm and 170 nm. This embodiment, compared with the prior art (the thickness of the first hole transport sub-unit 311 of the green light emitting device G is about 45 nm), balances the transport rates of holes and electrons by increasing the thickness G H of the first hole transport sub-unit 311 of the green light emitting device G, i.e. the length of the hole transport path, to reduce the hole transport rate, so that the holes and the electrons are recombined in the first light emitting layer GEML1, thereby ensuring the light emitting stability of the green light emitting device G.

[0079] Optionally, the thickness G H of the first hole transport sub-unit 311 is 130 nm, 150 nm or 170 nm.

[0080] In one possible embodiment, as shown in Figure 4 As shown, when the light emitting device is a blue light emitting device B, the thickness B H of the first hole transport sub-unit 311 is between 90 nm and 130 nm. This embodiment, compared with the prior art (the thickness of the first hole transport sub-unit 311 of the blue light emitting device B is about 35 nm), balances the transport rates of holes and electrons by increasing the thickness B H of the first hole transport sub-unit 311 of the blue light emitting device B, i.e. the length of the hole transport path, to reduce the hole transport rate, so that the holes and the electrons are recombined in the first light emitting layer BEML1, thereby ensuring the light emitting stability of the blue light emitting device B.

[0081] In some embodiments, the first hole transport sub-unit 311 comprises at least one of a first hole injection layer HIL1, a first hole transport layer HTL1 and a first electron blocking layer EBL1.

[0082] For example, as shown in Figure 3 As shown, the first hole transport sub-unit 311 comprises, in sequence from the direction away from the anode 1, a first hole injection layer HIL1, a first hole transport layer HTL1 and a first electron blocking layer EBL1. The first hole injection layer HIL1 is mainly used to improve the hole injection efficiency, thereby improving the hole transport efficiency. The first hole transport layer HTL1 is mainly used to transport the holes generated by the anode 1 or the charge generation and separation unit 4, thereby improving the hole transport efficiency. The first electron blocking layer EBL1 is mainly used to block the electrons and transport the holes.

[0083] The thickness of the first electron blocking layer EBL1 of the light emitting device of different colors can be increased respectively to balance the transport rates of holes and electrons. And / or, the thickness of the first hole transport layer HTL1 of the light emitting device of different colors can be increased respectively to balance the transport rates of holes and electrons.

[0084] For example, as shown inFigure 4 As shown, the thickness of the first hole injection layer HIL1 corresponding to the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B is the same, for example, 10 nm. The thickness of the first hole transport layer HTL1 corresponding to the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B is the same, for example, 100 nm. The thickness of the first electron blocking layer EBL1 corresponding to the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B is different. For example, the thickness of the first electron blocking layer REBL1 corresponding to the red light-emitting device R is 90 nm; the thickness of the first electron blocking layer GEBL1 corresponding to the green light-emitting device G is 40 nm; and the thickness of the first electron blocking layer BEBL1 corresponding to the blue light-emitting device B is 5 nm.

[0085] In some embodiments, as Figure 4 As shown, the contact interface between the N-type doped charge generation layer N-CGL and the P-type doped charge generation layer P-CGL is the first surface. The distance from the first surface to the second surface of the first light-emitting layer EML1, which is closest to the N-type doped charge generation layer N-CGL, is denoted as the first distance L1. The first distance L1 is between 15 nm and 30 nm. This embodiment achieves a high-efficiency and stable tandem light-emitting device by adjusting the first distance L1, i.e., the length of the transmission path of the electrons generated by the charge generation and separation unit 4, to balance the transmission rate of the holes generated by the anode 1 and the transmission rate of the electrons generated by the charge generation and separation unit 4.

[0086] In a possible implementation, the first distance L1 may be adjusted by adjusting the thickness of the first electron transport subunit 312. Figure 3 or Figure 4 As shown, the first electron transport subunit 312 includes at least one first hole blocking layer HBL1. The first hole blocking layer HBL1 is mainly used to block holes, block metal ions doped in the N-type doped charge generation layer N-CGL, and transport electrons.

[0087] Specifically, the thickness of the first hole blocking layer HBL1 is between 5 nm and 10 nm.

[0088] Compared with the existing technology, this embodiment reduces the thickness of the first hole blocking layer HBL1, that is, shortens the length of the electron transmission path to increase the electron transmission rate, thereby balancing the transmission rates of holes and electrons, so that the two are combined in the first light-emitting layer EML1, and ensuring the luminous stability of the red light-emitting device R.

[0089] In another possible implementation, Figure 5 A schematic diagram of the specific structure of another carrier transport subunit provided in an embodiment of the present disclosure is shown in FIG. Figure 5As shown, the first electron transport sub-unit 312 includes a first hole blocking layer HBL1 and a first electron transport layer ETL1, and the first hole blocking layer HBL1 is closer to the first light-emitting layer EML1 than the first electron transport layer ETL1. The first electron transport layer ETL1 is mainly used to transport the electrons generated by the charge generation and separation unit 4, so as to improve the electron transport efficiency.

[0090] Specifically, the thickness of the first hole blocking layer HBL1 is between 5 nm and 10 nm. The thickness of the first electron transport layer ETL1 is between 5 nm and 30 nm. By thinning the thickness of the first hole blocking layer HBL1 and / or the first electron transport layer ETL1, that is, reducing the length of the electron transport path, the electron transport rate can be improved, so as to balance the transport rates of holes and electrons, and make them recombine in the first light-emitting layer EML1, thereby ensuring the light-emitting stability of the red light-emitting device R.

[0091] In some embodiments, as shown in FIG. 1, the charge generation and separation unit 4 includes an N-type doped charge generation layer N-CGL and a P-type doped charge generation layer P-CGL arranged in sequence away from the anode 1. Figure 4 As shown, the charge generation and separation unit 4 includes an N-type doped charge generation layer N-CGL and a P-type doped charge generation layer P-CGL arranged in sequence away from the anode 1; the surface of the N-type doped charge generation layer N-CGL and the P-type doped charge generation layer P-CGL in contact is a first surface; the surface of the second light-emitting layer EML2 close to the N-type doped charge generation layer N-CGL is a third surface, and the distance from the third surface to the first surface closest thereto is a second distance L2. Here, the second distance L2 can be understood as the transport distance of the holes generated by the charge generation and separation unit 4, that is, the length of the hole transport path from the starting point of generation to the second light-emitting layer EML2.

[0092] Alternatively, for the first light-emitting unit 31 away from the anode 1 side of the charge generation and separation unit 4, the distance from the surface of the first light-emitting unit 31 close to the N-type doped charge generation layer N-CGL to the first surface also represents the length of the hole transport path from the starting point of generation to the first light-emitting layer EML1. For the convenience of understanding, the present disclosure takes one first light-emitting unit 31 and one second light-emitting unit 32 as an example for illustration, and the case of multiple first light-emitting units 31 is not described herein.

[0093] The surface of the second light-emitting layer EML2 close to the cathode 2 side is a fourth surface, and the shortest distance from the fourth surface to the cathode 2 is a third distance L3, which can be understood as the transport distance of the electrons generated by the cathode 2, that is, the length of the electron transport path from the starting point of generation to the second light-emitting layer EML2.

[0094] Since the materials of the light-emitting layers of different color light-emitting devices are different, the materials of the sub-film layers in the first hole transport sub-unit 311 can be different, and therefore the hole mobility corresponding to different color light-emitting devices and the energy level difference between the film layers are different.

[0095] Specifically, as shown in FIG. 6, when the light emitting device is the red light emitting device R, the ratio of the second distance R_L2 to the third distance L3 is between 2 and 3.2. The present embodiment adjusts the second distance R_L2 of the hole transport path and the third distance L3 of the electron transport path in the second light emitting unit 32 corresponding to the red light emitting device R, and the ratio of the second distance R_L2 to the third distance L3 is between 2 and 3.2, so as to ensure the balance of the carrier (hole and electron) transmission in the red light emitting device R. Figure 4 Specifically, as shown in FIG. 7, when the light emitting device is the green light emitting device G, the ratio of the second distance G_L2 to the third distance L3 is between 1.8 and 2.8. The present embodiment adjusts the second distance G_L2 of the hole transport path and the third distance L3 of the electron transport path in the second light emitting unit 32 corresponding to the green light emitting device G, and the ratio of the second distance G_L2 to the third distance L3 is between 1.8 and 2.8, so as to ensure the balance of the carrier (hole and electron) transmission in the green light emitting device G.

[0096] Figure 4 Specifically, as shown in FIG. 8, when the light emitting device is the blue light emitting device B, the ratio of the second distance B_L2 to the third distance L3 is between 1.6 and 2.6. The present embodiment adjusts the second distance B_L2 of the hole transport path and the third distance L3 of the electron transport path in the second light emitting unit 32 corresponding to the blue light emitting device B, and the ratio of the second distance B_L2 to the third distance L3 is between 1.6 and 2.6, so as to ensure the balance of the carrier (hole and electron) transmission in the blue light emitting device B.

[0097] Specifically, as shown in FIG. 9, when the light emitting device is the red light emitting device R, the second distance R_L2 is between 80 nm and 110 nm. Compared with the prior art (the second distance of the red light emitting device R is less than 80 nm), the present embodiment increases the second distance R_L2 of the red light emitting device R, i.e. the length of the hole transport path, so as to reduce the hole transport rate, balance the hole and electron transport rates, and make them recombine in the first light emitting layer REML1, thereby ensuring the light emitting stability of the red light emitting device R. Figure 4 Optionally, the second distance R_L2 is 85 nm, 95 nm or 110 nm.

[0098] Figure 4 In a possible implementation, as shown in FIG. 10, when the light emitting device is the green light emitting device G, the second distance G_L2 is between 80 nm and 110 nm. Compared with the prior art (the second distance of the green light emitting device G is less than 80 nm), the present embodiment increases the second distance G_L2 of the green light emitting device G, i.e. the length of the hole transport path, so as to reduce the hole transport rate, balance the hole and electron transport rates, and make them recombine in the first light emitting layer REML1, thereby ensuring the light emitting stability of the green light emitting device G.

[0099] Optionally, the second distance G_L2 is 85 nm, 95 nm or 110 nm.

[0100] In a possible implementation, as shown in FIG. 11, when the light emitting device is the blue light emitting device B, the second distance B_L2 is between 80 nm and 110 nm. Compared with the prior art (the second distance of the blue light emitting device B is less than 80 nm), the present embodiment increases the second distance B_L2 of the blue light emitting device B, i.e. the length of the hole transport path, so as to reduce the hole transport rate, balance the hole and electron transport rates, and make them recombine in the first light emitting layer REML1, thereby ensuring the light emitting stability of the blue light emitting device B. Figure 4 ​​As shown, when the light-emitting device is a green light-emitting device G, the second distance G_L2 is between 65nm and 95nm. Compared with the prior art (the second distance of the green light-emitting device G is approximately 60nm), this embodiment increases the second distance G_L2 of the green light-emitting device G, that is, the length of the hole transmission path, to reduce the hole transmission rate, thereby balancing the transmission rates of holes and electrons, allowing them to recombine in the first light-emitting layer GEML1, and ensuring the luminous stability of the green light-emitting device G.

[0101] Optionally, the second distance G_L2 is 65 nm, 85 nm or 95 nm.

[0102] In one possible implementation, Figure 4 As shown, when the light-emitting device is a blue light-emitting device B, the second distance B_L2 is between 55nm and 85nm. Compared with the prior art (the second distance of the blue light-emitting device B is approximately 50nm), this embodiment increases the second distance B_L2 of the blue light-emitting device B, that is, the length of the hole transmission path, to reduce the hole transmission rate, thereby balancing the transmission rates of holes and electrons, allowing them to recombine in the first light-emitting layer BEML1, and ensuring the luminous stability of the blue light-emitting device B.

[0103] Optionally, the second distance B_L2 is 55 nm, 70 nm or 85 nm.

[0104] In some embodiments, as Figure 4 As shown, when the light-emitting device is a red light-emitting device R, the method of increasing the second distance R_L2 of the red light-emitting device R specifically includes: the thickness of the second hole transport subunit 321 can be set between 70nm and 90nm, and the second distance R_L2 of the red light-emitting device R is increased by increasing the thickness of the second hole transport subunit 321.

[0105] like Figure 4 As shown, when the light-emitting device is a green light-emitting device G, the method of increasing the second distance G_L2 of the green light-emitting device G specifically includes: the thickness of the second hole transport subunit 321 can be set between 60nm and 80nm, and the second distance G_L2 of the green light-emitting device G can be increased by increasing the thickness of the second hole transport subunit 321.

[0106] like Figure 4 As shown, when the light-emitting device is a blue light-emitting device B, the method of increasing the second distance B_L2 of the blue light-emitting device B specifically includes: the thickness of the second hole transport subunit 321 can be set between 50nm and 70nm, and the second distance B_L2 of the blue light-emitting device B is increased by increasing the thickness of the second hole transport subunit 321.

[0107] In some possible implementations, the second hole transport subunit 321 includes at least one of a second hole transport layer HTL2 and a second electron blocking layer EBL2. Figure 3 and Figure 4 As shown, the second hole transport subunit 321 includes a second hole transport layer HTL2 and a second electron blocking layer EBL2 arranged in sequence along the direction away from the anode 1. The second hole transport layer HTL2 is mainly used to transport holes generated by the charge generation and separation unit 4 to improve the hole transport efficiency. The second electron blocking layer EBL2 is mainly used to block electrons and transport holes. Figure 5 As shown, the second hole transport subunit 321 includes a second hole injection layer HIL2 , a second hole transport layer HTL2 , and a second electron blocking layer EBL2 , which are sequentially arranged in a direction away from the anode 1 .

[0108] The transport rates of holes and electrons can be balanced by increasing the thickness of the second electron blocking layer EBL2 of light-emitting devices of different colors. And / or, the transport rates of holes and electrons can be balanced by increasing the thickness of the second hole transport layer HTL2 of light-emitting devices of different colors.

[0109] For example, Figure 4 As shown, the thickness of the second hole transport layer HTL2 corresponding to the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B can be the same, for example, 55 nm. The thickness of the second electron blocking layer EBL2 corresponding to the red light-emitting device R, the green light-emitting device G, and the blue light-emitting device B can be different. For example, the thickness of the second electron blocking layer EBL2 corresponding to the red light-emitting device R is 30 nm; the thickness of the second electron blocking layer EBL2 corresponding to the green light-emitting device G is 20 nm; and the thickness of the second electron blocking layer EBL2 corresponding to the blue light-emitting device B is 5 nm.

[0110] In some embodiments, as Figure 4 As shown, the surface of the second light-emitting layer EML2 near the cathode 2 is the fourth surface, and the shortest distance from the fourth surface to the cathode 2 is the third distance L3. The third distance L3 is between 30 nm and 50 nm. This embodiment achieves a high-efficiency and stable tandem light-emitting device by adjusting the third distance L3, that is, the length of the transmission path of the electrons generated by the cathode 2, to balance the transmission rate of the holes generated by the charge generation and separation unit 4 and the transmission rate of the electrons generated by the cathode 2.

[0111] In one possible implementation, Figure 4As shown, the second light-emitting unit 32 further comprises a second electron transport sub-unit 322 arranged close to the cathode 2 of the second light-emitting layer EML2. The thickness of the second electron transport sub-unit 322 is the third distance L3. The second electron transport sub-unit 322 comprises, in sequence from the direction away from the cathode 2, an electron injection layer EIL, an electron transport layer ETL, and a second hole blocking layer HBL2. Among them, the electron injection layer EIL is mainly used to improve the electron injection efficiency, thereby improving the electron transport efficiency. The electron transport layer ETL is mainly used to transport the electrons generated by the cathode 2, so as to improve the electron transport efficiency. The second hole blocking layer HBL2 is mainly used to block the hole electrons and transport the electrons.

[0112] In a possible implementation, as shown in FIG. 1, the first light-emitting unit 31 further comprises a first electron transport sub-unit 312 arranged close to the anode 1 of the first light-emitting layer EML1. Figure 5 As shown, the second light-emitting unit 32 further comprises a second electron transport sub-unit 322 arranged close to the cathode 2 of the second light-emitting layer EML2. The second electron transport sub-unit 322 comprises, in sequence from the direction away from the cathode 2, an electron injection layer EIL, a second electron transport layer ETL2, and a second hole blocking layer HBL2.

[0113] In addition, the present disclosure can also adjust the hole transport material to select a hole transport material capable of balancing the hole and electron transport efficiency.

[0114] In some embodiments, the first hole transport sub-unit 311 at least comprises a first hole transport layer HTL1; the second hole transport sub-unit 321 at least comprises a second hole transport layer HTL2; and the structural general formula (I) of the material of the first hole transport layer HTL1 and the material of the second hole transport layer HTL2 is as follows:

[0115]

[0116] Among them, Ar1-Ar3 are each independently selected from any one of hydrogen, deuterium, nitrile group, nitro group, hydroxyl group, carbonyl group, ester group, imide group, amide group, alkyl group, cycloalkyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, alkenyl group, silyl group, boron group, amine group, aryl phosphine group, phosphine oxide group, aryl group, and heteroaryl group; or any adjacent groups in Ar1-Ar3 combine to form a ring; and N represents a nitrogen atom.

[0117] In some embodiments, the first hole transport sub-unit 311 at least comprises a first hole transport layer HTL1; the second hole transport sub-unit 321 at least comprises a second hole transport layer HTL2; and the structural general formula (II) of the material of the first hole transport layer HTL1 and the material of the second hole transport layer HTL2 is as follows:

[0118]

[0119] wherein Ar4to Ar7are each independently selected from any one of hydrogen, deuterium, nitrile group, nitro group, hydroxyl group, carbonyl group, ester group, imide group, amide group, alkyl group, cycloalkyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, alkenyl group, silyl group, boryl group, amine group, arylphosphine group, phosphine oxide group, aryl group, heteroaryl group; or any adjacent groups of Ar4to Ar7are combined to form a ring; L represents a substituted or unsubstituted arylene group or heteroarylene group.

[0120] In some embodiments, Ar1to Ar7are selected from any one of the following structures:

[0121]

[0122] wherein * represents the position of the structure general formula (I) or the position of the structure general formula (II).

[0123] The present embodiments achieve high-efficiency and stable tandem OLED devices by selecting the materials of the first hole transport layer HTL1 and the second hole transport layer HTL2 with adapted electron transport efficiency to match the electron injection and transport rates.

[0124] In some embodiments, L is selected from any one of the following structures:

[0125] In some embodiments, the cathode 2 and the anode 1 each independently comprise at least one selected from silver (Ag), magnesium (Mg), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), lithium fluoride / calcium (LiF / Ca), lithium fluoride / aluminum (LiF / Al), molybdenum (Mo), titanium (Ti), indium (In), tin (Sn), zinc (Zn), and ytterbium (Yb), or an oxide thereof. For example, when the light-emitting device is a top-emission structure device, the anode 1 is an electrode with reflectivity and the cathode 2 is an electrode with transmissivity or semi-transmissivity. For example, the anode 1 is selected from a material with high work function, such as an ITO / Ag / ITO stacked structure; and the cathode 2 is selected from a material with low work function, which can be a semi-transmissive metal or metal alloy material, such as an Ag / Mg alloy material.

[0126] In some embodiments, the material of the hole injection layer (e.g., the first hole injection layer HIL1 and the second hole injection layer HIL2) can include, but is not limited to, a p-type dopant of a strong electron-withdrawing system and a hole transport material doped together. Among them, the p-type dopant can include any one or more combinations of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyano-p- benzoquinone (F4TCNQ), 1,2,3-tris[(cyano)(4-cyano-2,3,5,6-tetrafluorophenyl)methylene] cyclopropane. The hole transport material can include any one or more combinations of arylamine hole transport material, dimethylfluorene hole transport material, carbazole hole transport material. For example, the hole transport material can include any one or more combinations of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (BAFLP), 4,4'-bis[N-(9,9-dimethylfluoren-2-yl)-N-phenylamino]biphenyl (DFLDPBi), 4,4'-di(9-carbazolyl) biphenyl (CBP), and 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (PCzPA).

[0127] In some embodiments, the material of the electron blocking layer (e.g., the first electron blocking layer EBL1 and the second electron blocking layer EBL2) can include, but is not limited to, any one or more combinations of arylamine electron blocking material, dimethylfluorene electron blocking material, carbazole electron blocking material. For example, the material of the electron blocking layer can include any one or more combinations of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (BAFLP), 4,4'-bis[N-(9,9-dimethylfluoren-2-yl)-N-phenylamino]biphenyl (DFLDPBi), 4,4'-di(9-carbazolyl) biphenyl (CBP), and 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (PCzPA).

[0128] In some embodiments, the material of the light-emitting layer (e.g., the first light-emitting layer EML1 and the second light-emitting layer EML2) can include one light-emitting material, or two or more light-emitting materials. For example, the material of the light-emitting layer can include a host light-emitting material and a guest light-emitting material doped into the host light-emitting material; the material of the light-emitting layer can include a light-emitting material having a thermally activated delayed fluorescence property at room temperature, a light-emitting material having a fluorescence property at room temperature, or a light-emitting material having a phosphorescence property at room temperature.

[0129] For example, when the light-emitting device is a red light-emitting device R, the material of the first light-emitting layer EML1 is a red light-emitting material, which can specifically include any one or a combination of multiple of DCM-based red light-emitting materials and metal complex-based red light-emitting materials. For example, the red light-emitting material can include any one or a combination of multiple of 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethylguercin-9-enyl)-4H-pyran (DCJTB), bis(1-phenylisoquinoline)(acetylacetone)iridium(III) (Ir(piq)2(acac)), octaethylporphyrin platinum (abbreviated as: PtOEP), bis(2-(2'-benzothienyl)pyridine-N,C3')(acetylacetone)iridium (abbreviated as: Ir(btp)2(acac).

[0130] For example, when the light-emitting device is a green light-emitting device G, the material of the first light-emitting layer EML1 is a green light-emitting material, which can specifically include any one or a combination of multiple of coumarin dyes, quinacridone copper derivative-based green light-emitting materials, polycyclic aromatic hydrocarbon-based green light-emitting materials, diamine anthracene derivative-based green light-emitting materials, carbazole derivative-based green light-emitting materials, and metal complex-based green light-emitting materials. For example, the green light-emitting material can include any one or a combination of multiple of coumarin 6 (C-6), coumarin 545T (C-525T), quinacridone copper (QA), N,N'-dimethylquinacridone (DMQA), 5,12-diphenyl naphthacene (DPT), N10,N10'-diphenyl-N10,N10'-dibenzoyl-9,9'-dianthracene-10,10'-diamine (abbreviated as: BA-NPB), tris(8-hydroxyquinoline)aluminum(III) (abbreviated as: Alq3), tris(2-phenylpyridine)iridium (Ir(ppy)3), bis(2-phenylpyridine)iridium (Ir(ppy)2(acac)).

[0131] Exemplarily, when the light-emitting device is a blue light-emitting device B, the material of the first light-emitting layer EML1 is a blue light-emitting material, which can specifically include any one or more combinations of pyrene derivative blue light-emitting materials, anthracene derivative blue light-emitting materials, fluorene derivative blue light-emitting materials, perylene derivative blue light-emitting materials, styrylamine derivative blue light-emitting materials and metal complex blue light-emitting materials. For example, the blue light-emitting material may include any one or more combinations of N1,N6-di([1,1'-biphenyl]-2-yl)-N1,N6-di([1,1'-biphenyl]-4-yl)pyrene-1,6-diamine, 9,10-di-(2-naphthyl)anthracene (ADN), 2-methyl-9,10-di-2-naphthylanthracene (MADN), 2,5,8,11-tetra-tert-butylperylene (TBPe), 4,4'-bis[4-(diphenylamino)phenylvinyl]biphenyl (BDAVBi), 4,4'-bis[4-(di-p-tolylamino)phenylvinyl]biphenyl (DPAVBi), and bis(4,6-difluorophenylpyridine-C2,N)picolinyliridium (FIrpic).

[0132] In some embodiments, the material of the hole blocking layer (e.g., the first hole blocking layer HBL1 and the second hole blocking layer HBL2) may include, but is not limited to, aromatic heterocyclic hole blocking materials. Specifically, the hole blocking materials may include any one or more combinations of benzimidazole and its derivatives, imidazopyridine and its derivatives, benzimidazolophenanthridine derivatives, pyrimidine and its derivatives, triazine derivatives, pyridine and its derivatives, pyrazine and its derivatives, quinoxaline and its derivatives, diazole and its derivatives, quinoline and its derivatives, isoquinoline derivatives, phenanthroline derivatives, diazaphospholes, phosphine oxides, aromatic ketones, lactams, and boranes. For example, the material of the hole blocking layer may include any one or more combinations of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (p-EtTAZ), bathophenanthroline (BPhen), (BCP), and 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (BzOs).

[0133] In some embodiments, the material of the electron transport layer ETL (or the first electron transport layer ETL1 and the second electron transport layer ETL2) includes, but is not limited to, benzimidazole derivatives, imidazopyridine derivatives, benzimidazophenanthroline derivatives and other imidazole derivatives; pyrimidine derivatives, triazine derivatives and other oxazine derivatives; quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives and other compounds containing nitrogen-containing six-membered ring structures (also including compounds having phosphine oxide-containing substituents on the heterocycle, such as OXD-7, TAZ, p-EtTAZ), BPhen, BCP and the like.

[0134] In some embodiments, the material of the electron injection layer EIL includes, but is not limited to, compounds of one or more combinations of Li, Yb, Mg, Ca.

[0135] For the convenience of understanding, the materials of various film layers in the light-emitting device are listed and described below with one specific example.

[0136] The hole injection layer (e.g., the first hole injection layer HIL1 and the second hole injection layer HIL2) and the P-type doped charge generation layer P-CGL both include a hole injection material HIL’ and a hole transport material HTL’ doped together, wherein the molecular structure of the hole injection material HIL’ is: The molecular structure of the hole transport material HTL’ is:

[0137] The molecular structure of the material of the electron blocking layer (the first electron blocking layer REBL1 and the second electron blocking layer REBL2) corresponding to the red light-emitting device R is:

[0138] The molecular structure of the material of the electron blocking layer (the first electron blocking layer GEBL1 and the second electron blocking layer GEBL2) corresponding to the green light-emitting device G is:

[0139] The molecular structure of the material of the electron blocking layer (the first electron blocking layer BEBL1 and the second electron blocking layer BEBL2) corresponding to the blue light-emitting device B is:

[0140] The material of the light-emitting layer (the first light-emitting layer REML1 and the second light-emitting layer REML2) corresponding to the red light-emitting device R includes a host material (RH) and a guest material (RD), wherein the host material (RH) includes a P-type doped host material (RH_P) and an N-type doped host material (RH_N). The molecular structure of the P-type doped host material (RH_P) is: The molecular structure of the N-type doped host material (RH_N) is: The molecular structure of the guest material (RD) is Exemplarily, the doping mass ratio of the P-type doped host material (RH_P) and the N-type doped host material (RH_N) is 1:1.

[0141] The material of the light-emitting layer (the first light-emitting layer GEML1 and the second light-emitting layer GEML2) corresponding to the green light-emitting device G includes a host material (GH) and a guest material (GD), wherein the host material (GH) includes a P-type doped host material (GH_P) and an N-type doped host material (GH_N). The molecular structure of the P-type doped host material (GH_P) is as follows: The molecular structure of the N-type doped host material (GH_N) is as follows: The molecular structure of the guest material (GD) is as follows: Exemplarily, the doping mass ratio of the P-type doped host material (GH_P) and the N-type doped host material (GH_N) is 1:1.

[0142] The material of the light-emitting layer (the first light-emitting layer BEML1 and the second light-emitting layer BEML2) corresponding to the blue light-emitting device B includes a host material (BH) and a guest material (BD). The molecular structure of the host material (BH) is as follows: The molecular structure of the guest material (BD) is as follows:

[0143] The molecular structure of the material of the N-type doped charge generation layer N-CGL is as follows:

[0144] The molecular structure of the material of the hole blocking layer (for example, the first hole blocking layer HBL1 and the second hole blocking layer HBL2) is as follows:

[0145] The material of the electron transport layer ETL (or the first electron transport layer ETL1 and the second electron transport layer ETL2) includes an electron transport material ETL' and Liq doped together. The molecular structure of the electron transport material ETL' is as follows: The molecular structure of Liq is as follows: Exemplarily, the doping mass ratio of the two is 1:1.

[0146] The above is a detailed description of the structure and material of the light-emitting device.

[0147] For the light-emitting device formed by each of the above embodiments and combinations thereof, in order to verify the effect of the improved structure of the light-emitting device, the present disclosure randomly selects and verifies the light-emitting device under several embodiments by intercalation method, which proves that by increasing the thickness of the first hole transport subunit 311 and / or the second hole transport subunit 321, the transmission rate of the carriers can be effectively balanced, and the high efficiency and stability of the series light-emitting device are ensured.

[0148] The device structure of the intercalation method, a verification light-emitting layer different from the light-emitting color of the first light-emitting layer EML1 is inserted in the individual light-emitting device. If the verification light-emitting layer emits light, it indicates that the carrier recombination center deviates from the first light-emitting layer EML1, and the recombination occurs at the verification light-emitting layer, which affects the light-emitting efficiency and the service life of the light-emitting device. If the verification light-emitting layer does not emit light, it indicates that the carrier recombination center does not deviate from the first light-emitting layer EML1, and the recombination occurs at the first light-emitting layer EML1, which does not affect the light-emitting efficiency of the light-emitting device.

[0149] Comparative Example 1: Device structure of red light-emitting device R, ITO→HTL’:HIL’, 97:3, 10 nm→HTL1, 20 nm→REBL1, 35 nm→REML1(RH:RD, 5%), 40 nm→Verification EML1(GH:GD, 10%), 3 nm→HBL1, 5 nm→N-CGL(CGL:Li, 1%), 20 nm→P-CGL(HTL’:HIL’, 90:10), 10 nm→HTL2, 35 nm→REBL2, 35 nm→REML2(RH:RD, 5%), 40 nm→Verification EML2(GH:GD, 10%), 3 nm→HBL2, 5 nm→ETL’:Liq, 1:1, 30 nm→Yb, 1 nm→Mg:Ag, 13 nm→CPL, 60 nm.

[0150] Comparative Example 1: Device structure of red light-emitting device R, ITO→HTL’:HIL’, 97:3, 10 nm→HTL1, 20 nm→REBL1, 35 nm→REML1(RH:RD, 5%), 40 nm→Verification EML1(GH:GD, 10%), 3 nm→HBL1, 5 nm→N-CGL(CGL:Li, 1%), 20 nm→P-CGL(HTL’:HIL’, 90:10), 10 nm→HTL2, 35 nm→REBL2, 35 nm→REML2(RH:RD, 5%), 40 nm→Verification EML2(GH:GD, 10%), 3 nm→HBL2, 5 nm→ETL’:Liq, 1:1, 30 nm→Yb, 1 nm→Mg:Ag, 13 nm→CPL, 60 nm.

[0151] Comparative Example 2: Device structure of green light emitting device G, ITO→HTL':HIL', 97:3, 10 nm→HTL1, 20 nm→GEBL1, 15 nm→GEML1(GH:GD, 10%), 30 nm→EML1(RH:RD, 10%), 3 nm→HBL1, 5 nm→N-CGL(CGL:Li, 1%), 20 nm→P-CGL(HTL':HIL', 90:10), 10 nm→HTL2, 35 nm→GEBL2, 15 nm→GEML2(GH:GD, 10%), 30 nm→EML2(RH:RD, 10%), 3 nm→HBL2, 5 nm→ETL':Liq, 1:1, 30 nm→Yb, 1 nm→Mg:Ag, 13 nm→CPL, 60 nm.

[0152] Example 2: Device structure of green light emitting device G, ITO→HTL':HIL', 97:3, 10 nm→HTL1, 100 nm→GEBL1, 40 nm→GEML1(GH:GD, 10%), 30 nm→EML1(RH:RD, 10%), 3 nm→HBL1, 5 nm→N-CGL(CGL:Li, 1%), 20 nm→P-CGL(HTL':HIL', 90:10), 10 nm→HTL2, 55 nm→GEBL2, 20 nm→GEML2(GH:GD, 10%), 30 nm→EML2(RH:RD, 10%), 3 nm→HBL2, 5 nm→ETL':Liq, 1:1, 30 nm→Yb, 1 nm→Mg:Ag, 13 nm→CPL, 60 nm.

[0153] Comparative Example 3: Device structure of blue light emitting device B, ITO→HTL':HIL', 97:3, 10 nm→HTL1, 20 nm→BEBL1, 5 nm→BEML1(BH:BD, 2%), 7 nm→EML1(RH:RD, 10%), 3 nm→HBL1, 5 nm→N-CGL(CGL:Li, 1%), 20 nm→P-CGL(HTL':HIL', 90:10), 10 nm→HTL2, 35 nm→BEBL2, 5 nm→BEML2(BH:BD, 2%), 7 nm→EML2(RH:RD, 10%), 3 nm→HBL2, 5 nm→ETL':Liq, 1:1, 30 nm→Yb, 1 nm→Mg:Ag, 13 nm→CPL, 60 nm.

[0154] Example 3: Device structure of blue light-emitting device B, ITO→HTL’:HIL’, 97:3, 10 nm→HTL1, 100 nm→BEBL1, 5 nm→BEML1(BH:BD, 2%), 7 nm→EML1(RH:RD, 10%), 3 nm→HBL1, 5 nm→N-CGL(CGL:Li, 1%), 20 nm→P-CGL(HTL’:HIL’, 90:10), 10 nm→HTL2, 55 nm→BEBL2, 5 nm→BEML2(BH:BD, 2%), 7 nm→EML2(RH:RD, 10%), 3 nm→HBL2, 5 nm→ETL’:Liq, 1:1, 30 nm→Yb, 1 nm→Mg:Ag, 13 nm→CPL, 60 nm.

[0155] It should be noted that in the above Comparative Examples 1-3 and Examples 1-3, “→” refers to the order from anode to cathode to light extraction layer CPL. The front and back of “→” respectively represent different film layer structures. “HTL’:HIL’, 97:3” means that the HTL’ material and the HIL’ material are doped, and the mass doping ratio of the two is 97:3. “RH:RD, 10%” means that the RH material and the RD material are doped, and 10% means that the mass doping concentration of the RD material is 10%, that is, the ratio of the mass of the RD material to the sum of the mass of the RH material and the mass of the RD material. Similar parameter structures are the same, and the repeated parts are not described again.

[0156] The film layer materials of the above Comparative Examples 1-3 and Examples 1-3 can be selected in combination of any of the above materials. The film layer materials of Comparative Example 1 and Example 1 are the same. The film layer materials of Comparative Example 2 and Example 2 are the same. The film layer materials of Comparative Example 3 and Example 3 are the same.

[0157] The comparative analysis of the above Comparative Examples 1-3 and Examples 1-3 is shown in Table 1.

[0158] Table 1

[0159] Comparative device film layer thickness (nm) Example device film layer thickness (nm) HTL1 20 100 REBL1 35 90 REBL2 35 30 GEBL1 15 40 GEBL2 15 20 BEBL1 5 5 BEBL2 5 5 HTL2 35 55

[0160] Under the current density of 15 mA / cm 2 The luminescent devices of the above Comparative Examples 1-3 and Examples 1-3 were measured respectively to obtain the device spectrum data as shown in Table 2.

[0161] Table 2

[0162] Comparative Examples 1-3 Examples 1-3 R device emission wavelength 622 nm, 550 nm 621 nm G device emission wavelength 625 nm, 553 nm 552 nm B device emission wavelength 622 nm, 459 nm 461 nm

[0163] The verification light-emitting layer of Comparative Example 1-3 emits light, which indicates that the carrier imbalance of the light-emitting device corresponding to Comparative Example 1-3 is consistent with the case where the center deviates from the first light-emitting layer EML1. In the light-emitting device consistent with the thickness relationship of the present disclosure, the verification light-emitting layer does not emit light, which indicates that the film thickness relationship of the light-emitting device provided by the present disclosure can effectively improve the carrier balance in the light-emitting device, which is conducive to improving the performance of the device.

[0164] For the light-emitting device formed by each of the above embodiments and combinations thereof, the effect of the improved light-emitting device is verified.

[0165] The molecular structure of the material of the hole transport layer of the light-emitting device of Comparative Example 4 is as follows:

[0166] The material of the hole transport layer of the light-emitting device of Example 4 is selected as Compound 1; the material of the hole transport layer of the light-emitting device of Example 5 is selected as Compound 2; the material of the hole transport layer of the light-emitting device of Example 6 is selected as Compound 3; the material of the hole transport layer of the light-emitting device of Example 7 is selected as Compound 4; the material of the hole transport layer of the light-emitting device of Example 8 is selected as Compound 5; the material of the hole transport layer of the light-emitting device of Example 9 is selected as Compound 6; the material of the hole transport layer of the light-emitting device of Example 10 is selected as Compound 7; the material of the hole transport layer of the light-emitting device of Example 11 is selected as Compound 8; the material of the hole transport layer of the light-emitting device of Example 12 is selected as Compound 9; and the material of the hole transport layer of the light-emitting device of Example 13 is selected as Compound 10. The material selection of the above-mentioned Compounds 1-10 is shown in Table 3.

[0167] Table 3

[0168]

[0169] Under the condition of a current density of 15 mA / cm2, the light-emitting devices of Comparative Example 4 and Examples 4-13 are measured to obtain the device voltage and the light-emitting efficiency (EQE); and under the condition of a brightness of 1000 nit, the light-emitting devices of Comparative Example 4 and Examples 4-13 are tested to obtain the device lifetime (LT95@1000 nit), as shown in Table 4.

[0170] Table 4

[0171] Hole transport material Voltage EQE Lifetime (LT95@1000 nit) Comparative Example 4 HTL 100％ 100％ 100％ Example 4 Compound 1 98％ 109％ 111％ Example 5 Compound 2 97％ 104％ 116％ Example 6 Compound 3 96％ 102％ 102％ Example 7 Compound 4 98％ 103％ 109％ Example 8 Compound 5 99％ 106％ 107％ Example 9 Compound 6 99％ 105％ 105％ Example 10 Compound 7 97％ 106％ 112％ Example 11 Compound 8 98％ 107％ 114％ Example 12 Compound 9 98％ 108％ 108％ Example 13 Compound 10 100％ 101％ 107％

[0172] As shown in Table 4, the selection of the material of the hole transport layer (the first hole transport layer HTL1 and the second hole transport layer HTL2) of the present disclosure, in combination with the actual film thickness, can realize a high-efficiency and long-life tandem device.

[0173] In addition, the present disclosure also provides a display panel, specifically including the above embodiments and a plurality of light-emitting devices of different colors in combination, to achieve efficient and stable full-color tandem light-emitting devices. The tandem light-emitting devices are, for example, tandem OLED devices.

[0174] In some embodiments, Figure 6 A schematic diagram of a display panel provided in an embodiment of the present disclosure is shown in FIG. Figure 6 As shown, a plurality of light-emitting devices of different colors include a red light-emitting device R, a green light-emitting device G and a blue light-emitting device B; the materials of the first electron blocking layer EBL1 corresponding to the red light-emitting device R, the green light-emitting device G and the blue light-emitting device B are different; the materials of the second electron blocking layer EBL2 corresponding to the red light-emitting device R, the green light-emitting device G and the blue light-emitting device B are different; the materials of the first light-emitting layer EML1 corresponding to the red light-emitting device R, the green light-emitting device G and the blue light-emitting device B are different; the materials of the second light-emitting layer EML2 corresponding to the red light-emitting device R, the green light-emitting device G and the blue light-emitting device B are different.

[0175] In some embodiments, a light-emitting device primarily includes an anode 1, a cathode 2, a plurality of light-emitting units disposed between the anode 1 and the cathode 2, and a charge generation and separation unit 4 disposed between adjacent light-emitting units. The plurality of light-emitting units includes at least a first light-emitting unit 31 and a second light-emitting unit 32, with the first light-emitting unit 31 being closer to the anode 1 than the second light-emitting unit 32. The first light-emitting unit 31 includes a first light-emitting layer EML1 and a first hole transport subunit 311 disposed within the first light-emitting layer EML1 near the anode 1. The second light-emitting unit 32 includes a second light-emitting layer EML2 and a second hole transport subunit 321 disposed within the second light-emitting layer EML2 near the anode 1. The charge generation and separation unit 4 includes an N-type doped charge generation layer N-CGL and a P-type doped charge generation layer P-CGL disposed sequentially in a direction away from the anode 1. The surface of the N-type doped charge generation layer N-CGL in contact with the P-type doped charge generation layer P-CGL is a first surface. The surface of the first light-emitting layer EML1 near the N-type doped charge generation layer N-CGL is a second surface. The distance between the first surface and the second surface is a first distance L1.

[0176] For the red light-emitting device R, the ratio of the thickness R_H of the first hole transport subunit 311 to the first distance L1 is between 6 and 10. For the green light-emitting device G, the ratio of the thickness G_H of the first hole transport subunit 311 to the first distance L1 is between 5 and 8. For the blue light-emitting device B, the ratio of the thickness B_H of the first hole transport subunit 311 to the first distance L1 is between 4 and 6.

[0177] The embodiment adjusts the distance of the hole transport path and the distance of the electron transport path in the first light emitting unit 31, so as to ensure the transport balance of the carriers (holes and electrons) in the light emitting device of each color.

[0178] In some embodiments, the thickness R_H of the first hole transport sub-unit 311 for the red light emitting device R is between 170 nm and 230 nm. The thickness G_H of the first hole transport sub-unit 311 for the green light emitting device G is between 130 nm and 170 nm. The thickness B_H of the first hole transport sub-unit 311 for the blue light emitting device B is between 90 nm and 130 nm.

[0179] The embodiment increases the length of the hole transport path of the light emitting device of each color, so as to reduce the hole transport rate, balance the transport rates of the holes and the electrons, and make the holes and the electrons recombine in the first light emitting layer EML1 corresponding to each color, so as to ensure the light emitting stability of the light emitting device of each color.

[0180] In some embodiments, the first distance is between 15 nm and 30 nm. The embodiment adjusts the first distance L1, i.e., the length of the transport path of the electrons generated by the charge generation and separation unit 4, so as to balance the transport rate of the holes generated by the anode 1 and the transport rate of the electrons generated by the charge generation and separation unit 4, and realize the high-efficiency and stable series light emitting device.

[0181] In some embodiments, the charge generation and separation unit 4 comprises an N-type doped charge generation layer N-CGL and a P-type doped charge generation layer P-CGL arranged in sequence in the direction away from the anode 1; the surface of the N-type doped charge generation layer N-CGL and the P-type doped charge generation layer P-CGL in contact is a first surface; the surface of the second light emitting layer EML2 close to the N-type doped charge generation layer N-CGL is a third surface, and the distance from the third surface to the first surface closest to the third surface is a second distance L2. The surface of the second light emitting layer EML2 close to the cathode 2 is a fourth surface, and the shortest distance from the fourth surface to the cathode 2 is a third distance L3.

[0182] For the red light emitting device R, the ratio of the second distance R_L2 to the third distance L3 is between 2 and 3.2. For the green light emitting device G, the ratio of the second distance G_L2 to the third distance L3 is between 1.8 and 2.8. For the blue light emitting device B, the ratio of the second distance B_L2 to the third distance L3 is between 1.6 and 2.6.

[0183] The embodiment adjusts the second distance L2 of the hole transport path and the third distance L3 of the electron transport path in the second light emitting unit 32, so as to ensure the transport balance of the carriers (holes and electrons) in the light emitting device of each color.

[0184] In some embodiments, for the red light emitting device R, the second distance R_L2 is between 80 nm and 110 nm. For the green light emitting device G, the second distance G_L2 is between 65 nm and 95 nm. For the blue light emitting device B, the second distance B_L2 is between 55 nm and 85 nm.

[0185] The present embodiment balances the transport rates of holes and electrons by increasing the length of the hole transport path of the light emitting device of each color, so that the holes and electrons recombine in the first light emitting layer EML1, thereby ensuring the light emitting stability of the light emitting device.

[0186] In some embodiments, for the red light emitting device R, the thickness of the second hole transport sub-unit 321 is between 70 nm and 90 nm; for the green light emitting device G, the thickness of the second hole transport sub-unit 321 is between 60 nm and 80 nm; for the blue light emitting device B, the thickness of the second hole transport sub-unit 321 is between 50 nm and 70 nm.

[0187] The present embodiment balances the transport rates of holes and electrons by increasing the length of the hole transport path of the light emitting device of each color, so that the holes and electrons recombine in the first light emitting layer EML1, thereby ensuring the light emitting stability of the light emitting device.

[0188] In some embodiments, as shown in FIG. 1, the display panel further comprises a light extraction layer CPL disposed on the side of the cathode 2 away from the anode 1. Figure 6

[0189] Here, the term “reuse” refers to the same film layer material and thickness.

[0190] In some embodiments, as shown in FIG. 1, the display panel further comprises a light extraction layer CPL disposed on the side of the cathode 2 away from the anode 1. Figure 6

[0191] The molecular structure of the material of the light extraction layer CPL is as follows:

[0192] For example, the thickness of the light extraction layer CPL is between 55 nm and 65 nm.

[0193] In some embodiments, the display panel further comprises an encapsulation layer 5 disposed on the side of the light extraction layer CPL away from the cathode 2. The encapsulation layer 5 can be a single layer structure or a combination of multiple layer structures. For example, when the encapsulation layer 5 is a multiple layer structure, it can comprise a first inorganic material layer, an organic material layer, and a second inorganic material layer disposed in sequence in the direction away from the cathode 2.​​

[0194] In addition, the display panel manufacturing method comprises S1-S16.

[0195] S1, ultrasonic treatment of the glass plate with indium tin oxide (ITO) in cleaning agent, rinsing in deionized water, ultrasonic oil removal in acetone-ethanol mixed solvent, baking in a clean environment to completely remove water, forming the anode 1 of the light emitting device.

[0196] S2, the glass substrate with anode 1 in S1 is placed in a vacuum chamber, vacuumed to 1×10 -5 ~ 1×10 -6 Pa, the hole injection material HIL' and the hole transport material HTL' are vacuum deposited on the anode 1 layer film with a doping mass ratio of 97:3, the material thickness is 10 nm, and the first hole injection layer HIL1 is formed.

[0197] S3, the first hole transport layer HTL1 is formed on the side of the first hole injection layer HIL1 away from the anode 1. The thickness of the first hole transport layer HTL1 is 10 nm.

[0198] S4, the first electron blocking layer EBL1 is formed on the side of the first hole transport layer HTL1 away from the hole main layer. The material and thickness of the first electron blocking layer EBL1 corresponding to the light emitting device of different colors are different, which can be referred to the above device structure.

[0199] S5, the first light emitting layer EML1 is formed on the side of the first electron blocking layer EBL1 away from the first hole transport layer HTL1. The first light emitting layer EML1 includes host material and guest material, which can be prepared by multi-source co-evaporation method. The host material, guest material and thickness in the light emitting device of different colors are different, which can be referred to the above device structure.

[0200] S6, the first hole blocking layer HBL1 is formed on the side of the first light emitting layer EML1 away from the first electron blocking layer EBL1. The thickness of the first hole blocking layer HBL1 is 5 nm.

[0201] S7, the N-type doped charge generation layer N-CGL is formed on the side of the first hole blocking layer HBL1 away from the first light emitting layer EML1. The material of the N-type doped charge generation layer N-CGL is doped by multiple materials, such as CGL:Li with a mass ratio of 9:1, which can be prepared by multi-source co-evaporation method. The thickness of the N-type doped charge generation layer N-CGL is 20 nm.

[0202] S8, a P-type doped charge generation layer P-CGL is formed on the side of the N-type doped charge generation layer N-CGL away from the first hole blocking layer HBL1. The material of the P-type doped charge generation layer P-CGL includes a hole injection material doped in a hole transport material at a mass fraction of 10%, and can be prepared by a multi-source co-evaporation method. The thickness of the P-type doped charge generation layer P-CGL is 10 nm.

[0203] S9, a second hole transport layer HTL2 is formed on the side of the P-type doped charge generation layer P-CGL away from the N-type doped charge generation layer N-CGL. The thickness of the second hole transport layer HTL2 is 55 nm.

[0204] S10, a second electron blocking layer EBL2 is formed on the side of the second hole transport layer HTL2 away from the P-type doped charge generation layer P-CGL. The material and thickness of the second electron blocking layer EBL2 corresponding to different color light emitting devices are different, and can be referred to the device structure described above.

[0205] S11, a second light emitting layer EML2 is formed on the side of the second electron blocking layer EBL2 away from the second hole transport layer HTL2. The second light emitting layer EML2 includes a host material and a guest material, and can be prepared by a multi-source co-evaporation method. The host material, the guest material and the thickness in different color light emitting devices are different, and can be referred to the device structure described above.

[0206] S12, a second hole blocking layer HBL2 is formed on the side of the second light emitting layer EML2 away from the second electron blocking layer EBL2. The thickness of the second hole blocking layer HBL2 is 5 mn.

[0207] S13, an electron transport layer ETL is formed on the side of the second hole blocking layer HBL2 away from the second light emitting layer EML2. The material of the electron transport layer ETL includes an electron transport material and Liq doped together at a mass ratio of 1:1, and can be prepared by a double-source co-evaporation method. The thickness of the electron transport layer ETL is 30 nm.

[0208] S14, an electron injection layer EIL is formed on the side of the electron transport layer ETL away from the second hole blocking layer HBL2. The material of the electron injection layer EIL can be Yb. The thickness of the electron injection layer EIL is 1 nm.

[0209] S15, a cathode 2 is formed on the side of the electron injection layer EIL away from the electron transport layer ETL. The material of the cathode 2 includes Mg and Al doped together at a mass ratio of 8:2, and can be prepared by a double-source co-evaporation method.

[0210] S16, a light extraction layer CPL is formed on the side of the cathode 2 away from the anode 1. The thickness of the light extraction layer CPL is 60 nm.

[0211] The substrate containing the light extraction layer CPL can be packaged by a glass UV packaging method. If the material TFE is packaged, LIF needs to be evaporated on the light extraction layer CPL or an organic material with a low refractive index n less than or equal to 1.6.

[0212] In addition, the display device can be any product with a display function, such as a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, a vehicle-mounted device, etc. Other essential components of the display device are understood by those skilled in the art and are not described here again, nor should they be considered as a limitation on the present disclosure.

[0213] It can be understood that the above embodiments are only exemplary embodiments adopted for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered as the protection scope of the present disclosure.

Claims

1. A light emitting device, comprising an anode, a cathode, a plurality of light emitting units arranged between the anode and the cathode, and a charge generation separation unit arranged between adjacent light emitting units; at least one first light emitting unit and one second light emitting unit are included in the plurality of light emitting units, and the first light emitting unit is closer to the anode than the second light emitting unit; the first light emitting unit comprises a first light emitting layer and a first hole transport sub-unit arranged on the first light emitting layer close to the anode; the second light emitting unit comprises a second light emitting layer and a second hole transport sub-unit arranged on the second light emitting layer close to the anode; the thickness of the first hole transport sub-unit of the first light emitting unit is greater than the thickness of the second hole transport sub-unit of the second light emitting unit.

2. The light-emitting device according to claim 1, wherein the charge generation separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer arranged in sequence away from the anode; the surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; the surface of the first light emitting layer close to the N-type doped charge generation layer is a second surface, and the distance from the first surface to the second surface is a first distance; when the light emitting device is a red light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 6 and 10; when the light emitting device is a green light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 5 and 8; when the light emitting device is a blue light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 4 and 6.

3. The light emitting device of claim 2, wherein, when the light emitting device is a red light emitting device, the thickness of the first hole transport sub-unit is between 170 nm and 230 nm; when the light emitting device is a green light emitting device, the thickness of the first hole transport sub-unit is between 130 nm and 170 nm; when the light emitting device is a blue light emitting device, the thickness of the first hole transport sub-unit is between 90 nm and 130 nm.

4. The light-emitting device according to claim 2, wherein the first distance is between 15 nm and 30 nm.

5. The light emitting device of claim 4, wherein, the first light emitting unit further comprises a first hole blocking layer arranged on the first light emitting layer close to the cathode; the thickness of the first hole blocking layer is between 5 nm and 10 nm. The light emitting device according to claim 1 , wherein: the charge generation separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer arranged in sequence away from the anode; the surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; the surface of the second light emitting layer close to the N-type doped charge generation layer is a third surface, and the distance from the third surface to the first surface closest thereto is a second distance; the surface of the second light emitting layer close to the cathode side is a fourth surface, and the shortest distance from the fourth surface to the cathode is a third distance; when the light emitting device is a red light emitting device, the ratio of the second distance to the third distance is between 2 and 3.

2. when the light emitting device is a green light emitting device, the ratio of the second distance to the third distance is between 1.8 and 2.8; when the light emitting device is a blue light emitting device, the ratio of the second distance to the third distance is between 1.6 and 2.

6.

7. The light-emitting device according to claim 6, wherein when the light emitting device is a red light emitting device, the second distance is between 80 nm and 110 nm; when the light emitting device is a green light emitting device, the second distance is between 65 nm and 95 nm; when the light emitting device is a blue light emitting device, the second distance is between 55 nm and 85 nm.

8. The light-emitting device according to claim 6 or 7, wherein when the light emitting device is a red light emitting device, the thickness of the second hole transport sub-unit is between 70 nm and 90 nm; when the light emitting device is a green light emitting device, the thickness of the second hole transport sub-unit is between 60 nm and 80 nm; when the light emitting device is a blue light emitting device, the thickness of the second hole transport sub-unit is between 50 nm and 70 nm.

9. The light-emitting device according to claim 1, wherein the first hole transport sub-unit comprises at least a first hole transport layer; the second hole transport sub-unit comprises at least a second hole transport layer; the structural general formula (I) of the material of the first hole transport layer and the material of the second hole transport layer is as follows: wherein, Ar1-Ar3 are each independently selected from any one of hydrogen, deuterium, nitrile group, nitro group, hydroxyl group, carbonyl group, ester group, imide group, amide group, alkyl group, cycloalkyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, alkenyl group, silyl group, boron group, amine group, aryl phosphine group, phosphine oxide group, aryl group, heteroaryl group; or, any adjacent groups among Ar1-Ar3 combine to form a ring; N represents a nitrogen atom.

10. The light-emitting device according to claim 1, wherein the first hole transport sub-unit comprises at least a first hole transport layer; the second hole transport sub-unit comprises at least a second hole transport layer; the structural general formula (II) of the material of the first hole transport layer and the material of the second hole transport layer is as follows: wherein, Ar4-Ar7 are each independently selected from any one of hydrogen, deuterium, nitrile group, nitro group, hydroxyl group, carbonyl group, ester group, imide group, amide group, alkyl group, cycloalkyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, alkenyl group, silyl group, boron group, amine group, aryl phosphine group, phosphine oxide group, aryl group, heteroaryl group; or, any adjacent groups among Ar4-Ar7 combine to form a ring; L represents a substituted or unsubstituted arylene group or heteroarylene group.

11. The light-emitting device according to claim 9 or 10, wherein Ar1-Ar7 are selected from any one of the following structures: wherein * indicates the position of the connecting structure of general structure (I) or the position of general structure (II).

12. The light-emitting device according to claim 10, wherein L is selected from any one of the following structures:

13. The light-emitting device according to claim 1, wherein the first hole transport sub-unit comprises a first hole injection layer, a first hole transport layer, and a first electron blocking layer arranged in sequence in a direction away from the anode; the second hole transport sub-unit comprises a second hole transport layer and a second electron blocking layer arranged in sequence in a direction away from the anode.

14. A display panel comprising a plurality of light emitting devices of different colors, the plurality of light emitting devices of different colors comprising a red light emitting device, a green light emitting device, and a blue light emitting device. The material of the first electron blocking layer corresponding to the red light emitting device, the green light emitting device and the blue light emitting device is different; the material of the second electron blocking layer corresponding to the red light emitting device, the green light emitting device and the blue light emitting device is different. The material of the first light emitting layer corresponding to the red light emitting device, the green light emitting device and the blue light emitting device is different; the material of the second light emitting layer corresponding to the red light emitting device, the green light emitting device and the blue light emitting device is different.

15. The display panel of claim 14, wherein, The light emitting device comprises an anode, a cathode, a plurality of light emitting units arranged between the anode and the cathode, and a charge generation separation unit arranged between adjacent light emitting units; the plurality of light emitting units comprises a first light emitting unit and a second light emitting unit, and the first light emitting unit is closer to the anode than the second light emitting unit; the first light emitting unit comprises a first light emitting layer and a first hole transport sub-unit arranged close to the anode of the first light emitting layer; the second light emitting unit comprises a second light emitting layer and a second hole transport sub-unit arranged close to the anode of the second light emitting layer; The charge generation separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer arranged in sequence away from the anode; the surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; the surface of the first light emitting layer close to the N-type doped charge generation layer is a second surface, and the distance from the first surface to the second surface is a first distance; For the red light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 6 and 10; for the green light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 5 and 8; for the blue light emitting device, the ratio of the thickness of the first hole transport sub-unit to the first distance is between 4 and 6.

16. The display panel of claim 15, wherein, For the red light emitting device, the thickness of the first hole transport sub-unit is between 170 nm and 230 nm; for the green light emitting device, the thickness of the first hole transport sub-unit is between 130 nm and 170 nm; for the blue light emitting device, the thickness of the first hole transport sub-unit is between 90 nm and 130 nm.

17. The display panel of claim 15 or 16, wherein, The first distance is between 15 nm and 30 nm.

18. The display panel of claim 14, wherein, The light emitting device comprises an anode, a cathode, a plurality of light emitting units arranged between the anode and the cathode, and a charge generation separation unit arranged between adjacent light emitting units; the plurality of light emitting units comprises a first light emitting unit and a second light emitting unit, and the first light emitting unit is closer to the anode than the second light emitting unit; the first light emitting unit comprises a first light emitting layer and a first hole transport sub-unit arranged close to the anode of the first light emitting layer; the second light emitting unit comprises a second light emitting layer and a second hole transport sub-unit arranged close to the anode of the second light emitting layer; The charge generation and separation unit comprises an N-type doped charge generation layer and a P-type doped charge generation layer sequentially arranged in a direction away from the anode; a surface of the N-type doped charge generation layer in contact with the P-type doped charge generation layer is a first surface; a surface of the second light-emitting layer close to the N-type doped charge generation layer is a third surface, and a distance from the third surface to the first surface closest thereto is a second distance; a surface of the second light-emitting layer close to the cathode is a fourth surface, and a shortest distance from the fourth surface to the cathode is a third distance; For the red light-emitting device, the ratio of the second distance to the third distance is between 2 and 3.2; for the green light-emitting device, the ratio of the second distance to the third distance is between 1.8 and 2.8; for the blue light-emitting device, the ratio of the second distance to the third distance is between 1.6 and 2.

6.

19. The display panel of claim 18, wherein, For the red light-emitting device, the second distance is between 80nm and 110nm; for the green light-emitting device, the second distance is between 65nm and 95nm; for the blue light-emitting device, the second distance is between 55nm and 85nm.

20. The display panel of claim 18, wherein, For the red light-emitting device, the thickness of the second hole transport subunit is between 70nm and 90nm; for the green light-emitting device, the thickness of the second hole transport subunit is between 60nm and 80nm; for the blue light-emitting device, the thickness of the second hole transport subunit is between 50nm and 70nm.

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